1. Field of the Invention
This invention relates to an improved process for producing hydrogen by contacting carbon monoxide under homogeneous conditions with an aqueous alkaline liquid medium containing a saturated paraffinic water-soluble alcohol and rhodium-containing catalyst.
2. Background of the Invention
The water gas shift reaction, referred to in the art as the "shift reaction", i.e., EQU CO+H.sub.2 O.revreaction.CO.sub.2 +H.sub.2
is well known and has been of great industrial importance for over 40 years. The reaction finds application, for example: in the large scale production of hydrogen for ammonia synthesis; in increasing the hydrogen to carbon monoxide ratio for methanation and in Fischer-Tropsch synthesis; in the treatment of combustion exhaust gases through carbon monoxide removal, and hydrogen generation for reducing nitrogen and sulfur oxides.
Heterogeneous catalysts are usually employed in the shift reaction and are either iron oxide and related oxides in which the process must be conducted at temperatures exceeding 350.degree. C., or copper metal, in which the process is conducted in the temperature range of about 200.degree. to 250.degree. C. However, at these required high temperatures, the equilibrium constant of the shift reaction becomes significantly smaller with increasing temperature.
Thus, a constant area of activity in this field revolves around the search for new improved conditions for conducting the shift reaction at lower temperatures and under more favorable equilibrium conditions.
Homogeneous catalysts, based on Group VIII metals, for conducting the shift reaction under more desirable low temperature conditions, are known and are described in J. Am. Chem. Soc. 99(8) pp 2792-3 (1977); J. Am. Chem. Soc., 99(1) pp. 252-3 (1977); U.S. Pat. No. 3,539,298 (1970); U.S. Pat. No. 3,490,872 (1970), and Japanese Patent Application No. 52056094. However, none of the references mention the use of a saturated paraffinic water-soluble alcohol as a catalytic reagent to increase the yield and rate of production of hydrogen at desired low temperatures in a homogeneous-process utilizing an aqueous alkaline liquid phase and a rhodium-containing catalyst.